JPS591303B2 - synthetic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synthetic resin composition having excellent mechanical properties and comprising polypropylene, calcium carbonate and dry wood flour.

The inventors of the present invention have previously discovered that a synthetic resin composition having the same composition as the present invention has particularly excellent paintability as a lacquerware base, and therefore has filed a patent application for a synthetic resin composition for a lacquerware base. Ta.

Through further research, the present inventors discovered that this synthetic resin composition has excellent mechanical properties as a material for various molded products other than lacquerware bases. Therefore, the present invention provides a synthetic resin composition that is inexpensive, has excellent mechanical properties, and can be used for things other than lacquerware bases. The synthetic resin used in the synthetic resin composition of the present invention is polypropylene. Polypropylene is widely available and has better heat resistance and moldability than other polyolefins. However, since polypropylene is obtained from petroleum, care must be taken when using it to the minimum necessary extent. Therefore, the present inventors considered wood powder as an extender for polypropylene. Wood powder is fairly inexpensive and can be obtained in large quantities because it can be used effectively for purposes other than wood boards and pillar materials. In this way, adding wood powder to polypropylene improves the bending strength, elastic modulus, heat strain temperature, and molding shrinkage rate. When adding powdered calcium carbonate produced by this method, it was surprisingly discovered that these physical properties were further improved. Moreover, these three components have good mutual affinity, and as a synthetic resin composition, other mechanical properties also exhibit values that pose no problem in practical use. The synthetic resin composition of the present invention consisting of the above three components is polypropylene 30
60% to 60% by weight, 30 to 50% by weight of calcium carbonate and 10 to 30% by weight of dry wood flour.

The polypropylene used in the present invention is a commercially available general product.
In addition to homopolymers, it also includes copolymers with propylene as the main component and ethylene. Calcium carbonate is 10
0 to 250 mesh, and wood powder is 80 to 200 mesh made by drying sharp maple, cedar, white birch, etc. with a moisture content of about 5 to 7% by weight. All of these are suitable as components of the synthetic resin composition of the present invention. Particularly suitable synthetic resin compositions of the present invention include 40 to 45% by weight of polypropylene, 35 to 40% by weight of calcium carbonate,
It consists of 15 to 20% by weight of dry wood flour.

If the amount of calcium carbonate or dry wood flour used is increased, it is advantageous in terms of price for the synthetic resin composition, but it is not preferable because the moldability becomes poor and the impact strength decreases. When the synthetic resin composition of the present invention requires particularly good moldability depending on the shape of the molded product, for example, atactic polypropylene with a molecular weight of About 25,000 to 35,000,
It may be added in an amount of 3 to 5% by weight.

In addition, if you want to particularly increase the surface hardness of the molded product,
An appropriate amount of talc may be added. The synthetic resin composition of the present invention can be produced by mixing the above mixture in a kneader to
After kneading at 0'C for about 1 minute, it is passed through an extruder and a pelletizer to form pellets, which can be used to obtain molded products of any shape by injection molding at a melting temperature of about 180 to 220C. can.

Next, the present invention will be explained in more detail with reference to comparative examples and examples.

Comparative Examples 1 to 3 As polypropylene, pellets of Sumitomo Noprene WlOl manufactured by Sumitomo Chemical Co., Ltd. were used alone, or mixed with 200 mesh of calcium carbonate powder, or mixed with 120 mesh of dry wood powder obtained from the woody part of maple. This was then mixed using an FCM Farrel type continuous kneading machine manufactured by Kobe Steel.
After melting and kneading at 200°C for 1 minute, the mixture is passed through an extruder and a pelletizer to form pellets.

Using this pellet, injection molding is performed to create a plate-shaped test piece. Various mechanical properties were measured for the obtained test piece, and the results are shown in Table 1. Example 1
~4 As the polypropylene, pellets of Sumitomo Noprene WlOl manufactured by Sumitomo Chemical Co., Ltd., 200 mesh calcium carbonate powder, 120 mesh dry wood powder obtained from the woody part of maple, or atactic polypropylene with a molecular weight of 25,000. It is mixed with pellets and mixed with the FCM Farrel type continuous mixer manufactured by Kobe Steel.
After melting and kneading for 1 minute at 0'C, the mixture is passed through an extruder and a pelletizer to form pellets.

Using this pellet, injection molding is performed to create a plate-shaped test piece. Various mechanical properties were measured for the obtained test piece 1, and the results are shown in Table 2.As is clear from the above table and Table 1, the synthetic resin composition according to the present invention has excellent mechanical properties. It can be seen that it has excellent physical properties and can be used satisfactorily as a base material for general molded products.

Claims (1)

[Claims] 1 30 to 60% by weight of polypropylene, 30 to 50% by weight of calcium carbonate, and 10 to 30% by weight of dry wood flour.
A synthetic resin composition characterized in that it is used for purposes other than lacquerware bases, to which % by weight is added.